Process of making lignin



Patented Apr. 25, 1939 g 2,156,159

UNITED STATES PATENT OFFICE PROCESS OF MAKING LIGNIN Edgar T. Olson,Marquette, Mich, and Raphael Katzen and Richard H. Plow, Phelps, Wis.,assignors to Northwood Chemical Company, Phelps, Wis., a corporation ofWisconsin No Drawing. Application'May 17, 1938,

Serial No. 208,499

'7 Claims. -(Cl. 260124) This invention relates to theart of making apressure of about 150 pounds per square inch. lignin, and isparticularly concerned with the A partially hydrolyzed-wood was obtainedconmaking of lignin containing varying small taining between 60% and 65%of lignin and beamounts of cellulose. tween 35% and 40% 01 cellulose.

5 According to the present 'process, lignin con- Example 2.Maple Woodsawdust or flour was 5 taining various amounts of cellulose is obtainedreduced to particle sizes which would pass thru from wood, corn stalks,straw, bagasse and simian 80 mesh, or finer, screen and was then mixedlar lignin-cellulose containing substances. The With'a 5% sulphuric acidsolution in the ratio of particular lignin-cellulose-containing materialto parts of such acid to 1 part of the dried wood 0 be subjected to. theprocess is first reduced to substance contained in such sawdust. Thismix- 10 particles which will pass thru a 5 mesh, or finer, ture washeated for about 2 minutes at a temperascreen. These particles are thenmixed with diture of about 220 C. under a pressure of about lutesulphuric acid solution, that is, a solution 325 pounds per square inch.The wood obtained containing between about .4% and about 5% of from thistreatment contained between about 75% sulphuric acid, in the ratio ofbetween about '7 and 80% of lignin and between about and 5 parts andabout 10 parts of such dilute acidto of cellulose. one part of thefinely divided, dry material. This Example 3.-Maple wood sawdust or woodflour I mixture of acid and material is then heated for of a size whichpassed thru an 80 mesh, or liner, between about 2 minutes and about 5minutes at a. screen was mixed with a 5% sulphuric acid solu- 20temperature between about 165 C. and about tion in the ratio 0f10 partso the d to 1 Pa 20 280 C. at a pressure betweenabout 90 pounds and ofthe dry wood substance contained in the sawabout 100 pounds per squareinch. dust. This mixture was heated at a temperature At the end of theheating period the pressure of about 280 C. under a pressure of between800 is reduced to atmospheric pressure. The flash and 1000 pou ds PSquare inch for betWeen 25 vapors are preferably condensed and thefurfural, about 2 minutes and about 5 minutes. The wood 25 formic andacetic acids contained therein are material obtained from this treatmentcontained recovered. The remainder of the treated mabetween 90% and 95%of lignin a d b tween terial consisting of lignin-cellulose, hexoses,penand 10% 0f humie ac ds and Cellulose. toses, wood sugars and water isfiltered to sep In eneral, ot r hard and f wo 0 m arate the.lignin-cellulose materials from the stalks, Straw, bega se a d Otherlignin-eellulese 30 other substances, the latter'being subsequentlycompounds give results Comparable to these treated and recovered. Thelignin-oellulose ma- Examp e 1 t0 w Similarly treatedterials may bewashed, dried, pulverized and then In e a a ea n the Strength 01 theused or subjected to further treatment, sulphuric acid solutiondecreases the time re- Lignin-cellulose containing material of differquired for hydro y a likewise 85 the 35 out sizes may be treated by, thepresent process. perature and pressure increase the time of hydrol- Forexample, particles as large as 5 mesh size or y S d re s e ligninContent Varies directly even larger may be treated. Particles of 80 meshwith the degree of hyd o size have given satisfactory results but forcertain It W be understood that the heating p 40 reasons it isadvantageous to use even smaller a ove d sc bed ay b carried Out ySimple 4 40 particles. A convenient way to obtain the smaller p An a patus Which has b used Satparticles is to grind th m teri t t reduceisfactorily consisted of a metal tube thru which them in a colloid millto extremely small particle e mixture to be a e was moved y a D p size.l of conventional 'form capable of exerting the de- The followingexamples illustrate various spered pressure'on the contents of the tube.The 45 cific conditions under which the present invenube was p de w anautomatic p essur tion may be practiced. release valve at the dischargeend which permit- Errample 1.-Maple wood sawdust r flour s ted dischargeof the treated material at the prereduced to particles of a size whichwould pass determinedpressure. The tube and its contents thru an inchmesh, or finer, screen. This ma- Were heated to the desired temperatureby Passing 50 terial was then mixed with a 1% sulphuric id the tube thruan oil bath heated to the requisite solution in the ratio of 10 parts ofsuch acid to 1 temperaturepart of the dry wood substance contained inthe Having thus described th P e t invention sawdust. This mixture washeated for about 2 so that others may be able to understand and 55minutes at a temperature of about C. under practice the same, we statethat what we desire to I;

secure by Letters Patent is defined in what is claimed. i

What is claimed is:

1. The process of making lignin which comprises the steps of mixingfinely divided lignincellulose containing material with a dilutesolution of sulphuric acid, containing between about .4% and about 5% ofsulphuric acid, in the ratio from about 7 parts to about 10 parts ofsuch acid to about 1 part of the dry substance, heating such mixture tobetween about 165 C. and about 280 C. under pressure between about 90and 1000 pounds per square inch for between about two and about fiveminutes, and reducing the pressure to atmospheric.

2. The process of making lignin which comprises the steps of mixingfinely divided lignincellulose containing material .with a dilutesolution of sulphuric acid, containing between about 1% and about 5% ofsulphuric acid, in the ratio from about 7 parts of such acid to about 1part of the dry substance, heating such mixture to between about 165 C.and about 280 C. under pressures varying with the temperature andranging between about and 1000 pounds per square inch for between abouttwo and about five minutes, reducing the pressure to atmospheric,removing the vapors and recovering the lignin by filtration.

3. The process of making lignin which comprises the steps of mixingfinely divided lignincellulose containing material with a dilutesolution of sulphuric acid in the ratio from about 7 parts to about 10parts of such acid to about 1 part of the dry substance, heating suchmixture to between about 165 C. and about 280 C. under pressures betweenabout 90 pounds and about 1000 pounds per square inch, varying with thetemperature, for between about two and about five minutes, andrecovering the lignin, by separation of the liquid therefrom.

4. The process of making lignin which comprises the steps of mixinglignin-cellulose containing finely divided material, with several timesas many parts of a dilute solution of sulphuric acid. heating suchmixture to a temperature ranging from about 165 C. upwardly with thepressure, and subjecting such mixtureduring such heating to a pressureranging between about 90 and 1000 pounds per square inch forbetweenabout two and about five minutes, and reducing the pressure toatmospheric and recovering the lignin by known methods.

5. ,The process of making lignin which comprises the steps of mixingfinely divided lignincellulose containing material with several times asmany parts of a dilutesolution of sulphuric acid, heating such mixtureto about 165 C. under a pressure of about 90 pounds per square inch forbetween aboutt-wo and about five minutes, reducing the pressure toatmospheric and recovering the lignin by known methods.

6. The process of making lignin which com prises the steps of mixingfinely divided lignincellulose containing material with several times asmany parts of dilute sulphuric acid and continuously passing suchmixture thru a chamber in which the mixture is heated to between about165 C. and about 280 C. under pressures rang.- ing'between about 90pounds and about 1000 pounds per square inch for between about two andabout five minutes, continuously discharging from said chamber the thustreated mixture.

'7. The process of making lignin which comprises the steps of mixingfinely divided lignincellulose containing material with several times asmany parts of dilute sulphuric acid and continuously passing suchmixture through a chamber in which the mixture is heated to betweenabout 165 C. and about 280 C.- under pressure ranging between about 90pounds and about 1000 pounds per square inch, continuing such heatinguntil from about 50% to about of the lignincellulose containing materialhas been hydrolyzed, continuously discharging the thus treated mixturefrom said chamber, and recovering the lignin, by known methods.

EDGAR T. OLSON.

, RAPHAEL KATZEN. RICHARD H. PLOW.

